JPS60240749A - Rubber composition crosslinkable with amine - Google Patents

Abstract

PURPOSE:A crosslinkable rubber composition which gives a rubber with excellent heat resistance, using an amine as a crosslinking agent, and contains a copolymer comprising an ethylene unit, an acrylate unit, and a maleic anhydride unit, and a polyamine. CONSTITUTION:A rubber composition which contains an ethylene copolymer (A) crosslinkable with an amine and having a MI of 10 or higher, comprising 53- 86.6mol% ethylene unit of formula I, 13-45mol% acrylate unit of formula II(where R<1> is H or methyl; R<2> is a straight-chain or branched alkyl of 1-8C), and 0.2-5mol% maleic anhydride unit; and a primary or secondary polyamine (B) in a molar quantity of 0.125-2 times that of the maleic anhydride unit of the copolymer A. This composition gives a rubber of three-dimensional structure, with excellent heat resistance, resulting from the crosslinking of the maleic anhydride unit of the ethylene copolymer with the amine.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field of the Invention The present invention relates to an amine crosslinkable rubber composition, and more particularly to an amine crosslinkable rubber composition that provides rubber with excellent heat resistance through crosslinking.

PRIOR ART Attempts have been made to obtain rubber elastic bodies by diamine crosslinking of terpolymer copolymers of ethylene and acrylic acid nystelt maleic anhydride, but the compound of the copolymer (
Fillers, plasticizers, vulcanizing agents.

Mixed filling of anti-aging agent, lubricant, etc. and rubber) is kneaded.
Because scorching occurs during preparation using an extruder, etc., which is unfavorable for the physical properties of the final vulcanized product, maleic anhydride is modified with alcohol or monoamine and then copolymerized with ethylene. Post-modification of the terpolymer has been carried out, and there is no example of the terpolymer itself being used for diamine vulcanized rubber.

Purpose of the Invention Accordingly, an object of the present invention is to provide an amine crosslinkable rubber composition that uses an amine as a vulcanizing agent (or crosslinking agent) other than sulfur to provide a rubber with excellent heat resistance. .

Structure of the Invention The amine crosslinkable rubber composition according to the present invention contains (A) c) 53 to 86.6 mol% of ethylene units of the following formula (I),
(b) The following formula (13 to 45 moles of acrylate units of Irl π and C) The maleic anhydride unit α2 of the following formula [phase]
MI 10 or more amines consisting essentially of 5 molar amines, I
Crosslinkable ethylene copolymer (a) -CH2-CH2-(11 (b)-c-cH2-(Ir1 C=02 [wherein, R1 represents hydrogen or a methyl group, and R2 has a carbon number of 1 to 8 represents a linear or branched alkyl group]
Contains 5 to 5 times the molar amount of primary or Fi secondary polyamine.

Specific explanation of the structure and effects of the invention The crosslinkable ethylene copolymer (
~ represents 53-86.6 mol% of the ethylene unit (1), preferably 68-81.5 mol%, 13-45 mol% of the acrylate unit ([), preferably 16-39 mol%, and the maleic anhydride up to 12 to 5 moles of acid units,
Preferably, the M
I (measured at J I 8, same below) is over 10,
Preferably it is 50 or more.

The crosslinkable ethylene copolymer (ethylene unit in
) is less than 53 mol %, the crosslinked rubber will have poor bottom-filling brittleness, and conversely, if it exceeds 86.6 mol %, the rubber elasticity will be lost, which is not preferable. Furthermore, if the amount of acrylate units (fD) is less than 13 moles, ethylene crystals remain, resulting in loss of rubber elasticity.

On the other hand, if it exceeds 45 mol%, the low temperature properties will be lost, which is not preferable. Furthermore, if the amount of maleic anhydride units (2) is less than α2 mol %, there will be a shortage of crosslinking sites and the rubber elasticity (compression set and permanent elongation) will increase, whereas if it exceeds 5 mol, the rubber will become hard and the rubber elasticity will decrease. I don't like it being lost.

When the MI of the crosslinkable ethylene copolymer (A) is less than 10, the viscosity becomes high, so it becomes impossible to mix a crosslinking agent at low temperature, and a crosslinking reaction occurs during mixing, resulting in poor moldability and The physical properties of the resulting crosslinked product become unfavorable.

The crosslinkable ethylene copolymer (A) is ethylene.

It can be produced by copolymerizing an alkyl (meth)acrylate and maleic anhydride in the presence of a free radical polymerization initiator. The alkyl (meth)acrylate is represented by the general formula [wherein R1 represents a hydrogen atom or a methyl group, and R2 represents an alkyl group having 1 to 8 carbon atoms, preferably a methyl group, an ethyl group, a butyl group, a 2-ethylhexyl group, etc. ] Compounds represented by these can be used, specifically methyl (meth)acrylate, ethyl (methacrylate), and n-butyl (meth)acrylate.

(meth)acrylic acid t-butyl, (meth)acrylic acid 2
- Examples include ethylhexyl. The copolymerization is carried out using a high-pressure autoclave type reactor or a puller type reactor for high-pressure polyethylene at a temperature of, for example, 120-280°C and 500-280°C in ethylene monomer.
It can be carried out under the condition of 500 odors/102 G. Diethyl hexyl silver carbonate is used as a polymerization initiator.

t-butyl perpivalate, t-butyl peroxide,
benzoyl peroxide, dicumyl peroxide, t-
Butyl peroxy-2-ethylhexanoate,
2.5-dimethyl-di-t-butylberxyhexane and the like can be used. Constituent units of the produced copolymer (
I), (The moles of In and (to) can be controlled by appropriately selecting the reaction monomer ratio according to the type of monomers used, copolymerization reaction conditions, etc., and the MI of the copolymer depends on the monomers used. It can be adjusted by selecting the type and amount of polymerization initiator according to the type and copolymerization reaction conditions, or by using commonly known molecular weight regulators such as ethane, propane, butane, benzene,
Propylene, butene, alcohol, aldehyde, etc. are also MI
It can be used for adjustment.

The primary polyamine or secondary polyamine used as a crosslinking agent in the present invention is the crosslinkable ethylene copolymer c
It is used in an amount of 1125 to 5 times the weight of maleic anhydride units. If the amount of primary polyamine or secondary polyamine used is less than α125 molar times of maleic anhydride units (up to), crosslinking will be insufficient and sufficient rubber elasticity will not be exhibited. On the other hand, if it exceeds 5 times the mole t, not only will crosslinking become excessive, but unreacted amine will remain, which is unfavorable in terms of processing and product properties due to odor and the like.

Examples of the polyamine used as a crosslinking agent in the present invention include hexamethylene diamine.

These include primary diamines such as ethylene diamine, secondary diamines such as methylene dianiline, and polyamines such as tetraethylenepentamine. In addition, these can be used individually or as a mixture.

In the amine crosslinkable rubber composition according to the present invention, the maleic anhydride units of the ethylene copolymer are crosslinked with an amine to produce a rubber having a three-dimensional structure with excellent heat resistance. Compounding can be carried out under relatively mild conditions (e.g. 25 to 50°C), preferably in the presence of a crosslinking agent, a crosslinking aid, further an anti-aging agent, a lubricant, a mold release agent, a filler, etc. Therefore, there is an advantage that problems such as gelation due to local crosslinking reaction of maleic anhydride do not occur due to compounding under harsh conditions as in the conventional method. For crosslinking, commonly used compounding agents, such as antiaging agents such as 4,4'-bis(2,2'-dimethylenebenzyl)diphenylamine,
Plasticizer, octadecylamine.

A mold release agent such as stearic acid can be added. The crosslinking reaction is carried out by a conventionally known general method, for example, a compound of rubber, filler, and various compounding agents as described above is seeded with a roll or calendar roll, cut into a predetermined shape, and heated at 140°C. Heating can be carried out in one or two stages using electricity or steam at a temperature above 100 degrees.

Rubbers with a three-dimensional structure cross-linked with amines in this way generally have a residual elongation of t-
It is characterized by very good heat resistance that can be maintained at temperatures above 50°C. Even at fc-70°C, the isot impact is 509-tynlσ or more, and it has very good cold resistance. Furthermore, it has excellent rubber elasticity (compression set of 5 to 20 or less), vibration resistance, and oil resistance.

Therefore, the amine crosslinkable rubber composition of the present invention is suitable for automobile parts around engines that require heat resistance and oil resistance, as well as cold and oil resistant hoses, boots, and the like.

EXAMPLES The present invention will be explained in more detail with reference to Examples below, but it goes without saying that the scope of the present invention is not limited to these Examples. In the following examples, "department" and "
All figures are based on weight unless otherwise specified.

In addition, the physical properties of the raw bottoms obtained in the following examples were evaluated according to the following method. That is, the melt index of ethylene copolymer is determined by JIS K-6758 method, the tensile test of vulcanizate is determined by JIS K-6758 method, and the hardness test is determined by JIS K-6758 method.
6760 method, Izot impact is ASTM D25
6. Permanent elongation was measured according to JIS K-6301 method. The content of maleic anhydride in the copolymer was measured by potentiometric titration of a tetrahydrofuran solution of the copolymer with an aqueous NaOH solution.

The weight of the acrylic ester includes the total amount of the copolymer acrylic ester and maleic anhydride. After saponifying the copolymer acrylic ester and maleic anhydride to 100% with NaOH in a 6IBA/xylene solution, 1% with H2SO4.
The total amount of acrylic ester and maleic anhydride was measured by adding potentiometric drops with NaOH in the same manner as in the case of maleic anhydride, and maleic anhydride was obtained by subtracting -it of maleic anhydride. Determined by correcting 1 for acid.

Examples 1 to 6 and Comparative Examples 1 to 2 1) Production of ethylene copolymer Using a continuous autoclave with a capacity of 91 tons and equipped with a stirrer, ethylene, acrylic ester, maleic anhydride and/or
Alternatively, a mixture of a molecular weight regulator and a polymerization stabilizer is copolymerized in the presence of a free radical polymerization initiator (peroxide catalyst) under the pressure and pressure shown in Table 1 to form a terpolymer of 1!
l! Built. Note that maleic anhydride was dissolved in acrylic ester and supplied to the autoclave together with a polymerization inhibitor of 400 to 1000 pI)m.

The type of acrylic ester used, the polymerization conditions, and the composition and MI of the resulting copolymer were as shown in Table 1.

Margin below 2) Terpolymer 100 of Physical Property Evaluation Examples 1 to 6 and Comparative Examples 1 to 2
SRF carbon black 35P for each P■lB
i-IFt, polyester plasticizer 5 to 20 [see Table 2], aging inhibitor (Norguard) aPHR1 vulcanizing agent (hexamethylene diamine carbamate) 0.17 or 0.
25 mol (mol ratio relative to copolymerized maleic anhydride) (see Table 2), and 0.50 or 0.75 mol of vulcanization coagent (1,3-diphenylguanidine) [copolymerized % by mole based on maleic anhydride] (see Table 2) were mixed for 4 minutes at a flow rate of 30° C. and 40 revolutions/min using Labo Plastomill to obtain a compound.

The compound thus obtained was press vulcanized for 40 minutes at 125°C and 60°C pressure to obtain a vulcanized product. The physical properties of the vulcanized product at room temperature and after the vulcanizate was left in gear open at 190° C. for 70 hours were measured.

The results were as shown in Table 2.

Claims (1)

[Claims] 1. (A) (a) Ethylene unit 53- of the following formula (1)
86.6 mol%, (b) MIIO consisting essentially of 13 to 45 mol π of acrylate units of the following formula (In) and 0.2 to 5 mol π of maleic anhydride units of the following formula (to)
The above amine crosslinkable ethylene copolymer (a) 4C1-12-CH2-(111 [direction -〇-CH,2-(If) J0'2 [wherein, R1 represents hydrogen or a methyl group, R2 represents a linear or branched alkyl group having 1 to 8 carbon atoms] -CH-CH- α125 of the maleic anhydride unit amount of the copolymer C~
An amine crosslinkable rubber composition containing ~2 times the molar amount of a primary or secondary polyamine.